Azimilide Reduces Emergency Department Visits and Hospitalizations in Patients With an Implantable Cardioverter-Defibrillator in a Placebo-Controlled Clinical Trial

New formula for defining "normal" and "prolonged" QT in patients with bundle branch block

OBJECTIVES

To predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB).

BACKGROUND

There is no acceptable method for simple and reliable QT correction for patients with bundle branch block (BBB).

METHODS

We measured the QT interval in patients with new onset LBBB who had a recent electrocardiogram with narrow QRS for comparison. 48 patients who developed in-hospital LBBB were studied. Patients who had similar heart rate before and after LBBB were included. We used linear regression, the Bogossian method, and our new fixed QRS replacement method to evaluate the most reliable correction method.

RESULTS

JTc (QTc-QRS) interval was preserved before and after LBBB (328.9 ± 25.4 ms before LBBB vs. 327.3 ms post LBBB (p = 0.550). Mean predicted preLBBB QTc difference was 1.3 ms, -21.3 ms and 1.6 ms for the three methods respectively (p < 0.001 for Bogossian comparison with the other methods). Coefficients of correlation (R) between actual preLBBB QTc with predicted preLBBB QTc were 0.707, 0.683 and 0.665 respectively (p > 0.3 for R comparisons between all methods). The average absolute difference in preLBBB QTc was 15.5 ms and 16.7 ms for the regression and fixed-gender methods (p value between the two = 0.321) and 25.5 ms for the Bogossian method, which was found to be significantly underperforming.

CONCLUSIONS

In patients with LBBB, replacing of the QRS duration after deriving the QTc interval with a fixed value of 88 ms for female and 95 ms for male provides a simple and reliable method for predicting the QTc before the development of LBBB.

Results of a curtailed randomized controlled trial, evaluating the efficacy and safety of azimilide in patients with implantable cardioverter-defibrillators: The SHIELD-2 trial

BACKGROUND

Frequent hospital attendances in patients with implantable cardioverter-defibrillators (ICDs) result in significant morbidity and health care costs. Current drugs to reduce ICD shocks and hospital visits have limited efficacy and considerable toxicity. We evaluated the efficacy and safety of azimilide, a novel oral class III antiarrhythmic, for use in ICD patients.

METHODS

A total of 240 patients were enrolled in a prospective, randomized, double-blind, placebo-controlled trial to evaluate the effect of oral azimilide 75 mg daily in ICD patients with previously documented ventricular tachycardia or ventricular fibrillation, and a left ventricular ejection fraction ≤40%. The primary outcome metric was the adjudicated time-to-first unplanned cardiovascular (CV) hospitalization, or CV emergency department (ED) visit, or CV death. The trial was prematurely discontinued due to withdrawal of study sponsorship.

RESULTS

Azimilide demonstrated numerical but statistically nonsignificant reductions in the primary composite outcome (odds ratio [OR] 0.79, 95% CI 0.44-1.44), unplanned CV hospitalizations (OR 0.75, 95% CI 0.41-1.38), ED visits (OR 0.68, 95% CI 0.35-1.31), and all-cause shocks (OR 0.58, 95% CI 0.32-1.05). The incidence of adverse events was lower in the azimilide group. Neutropenia was not observed (absolute neutrophil count <1000 μ/L), and there was one possible torsade de pointes case that led to a successful ICD discharge.

CONCLUSION

The SHIELD-2 trial was statistically underpowered due to early trial termination and did not meet its primary objective. Despite this limitation, azimilide showed promise as a safe and effective drug in reducing all-cause shocks, unplanned hospitalizations, and ED visits in ICD patients.

ED evaluation and management of implantable cardiac defibrillator electrical shocks

Patients with implantable cardiac defibrillators not infrequently present to the emergency department after experiencing an implantable cardiac defibrillator shock. This review considers the management of such patients in the emergency department, including appropriate, inappropriate, and phantom shocks as well as electrical storm.

Electrical Storm: Incidence, Prognosis and Therapy

The term "electrical storm" indicates a life-threatening clinical condition characterized by the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, in particular in patients with ICD implanted for primary or secondary prevention. Although there isn't a shared definition of electrical storm, nowadays the most accepted definition refers to three or more separate arrhythmia episodes leading to ICD therapies including antitachycardia pacing or shock occurring over a single 24 hours' time period. Clinical presentation can be dramatic and triggering mechanism are not clear at all yet, but electrical storm is associated with high mortality rates and low patients quality of life, both in the acute phase and in the long term. The first line therapy is based on antiarrhythmic drugs to suppress electrical storm, but in refractory patients, interventions such as catheter ablation or in some cases surgical cardiac sympathetic denervation might be helpful. Anyhow, earlier interventional management can lead to better outcomes than persisting with antiarrhythmic pharmacologic therapy and, when available, an early interventional approach should be preferred.

Antiarrhythmic drugs 2013: state of the art

Antiarrhythmic drugs are widely used, but are of modest efficacy and have important side effects. However, even with the advance of catheter ablation for atrial fibrillation and ventricular tachycardia, antiarrhythmic drugs remain an important tool for treating arrhythmias. Antiarrhythmic drug development has remained slow despite much effort given our limited understanding of what role various ionic currents play in arrhythmogenesis and how they are modified by arrhythmias. This review will focus on promising new antiarrhythmic drugs undergoing clinical investigation or currently approved for clinical use, including amiodarone analogues, agents with novel ionic targets, and new drug combinations.

RBM25/LUC7L3 function in cardiac sodium channel splicing regulation of human heart failure

Alternative splicing is a posttranscriptional mechanism that can substantially change the pattern of gene expression. Up to 95% of human genes have multiexon alternative spliced forms, suggesting that alternative splicing is one of the most significant components of the functional complexity of the human genome. Nevertheless, alternative splicing regulation has received comparatively little attention in the study of cardiac diseases. When investigating SCN5A splicing abnormalities in heart failure (HF), we found that 47 of 181 known splicing regulators were upregulated in HF compared to controls, which indicates that splicing regulation may play a key role in HF. Our results show that angiotensin II and hypoxia, signals common to HF, result in increased LUC7L3 and RBM25 splicing regulators, increased binding of RBM25 to SCN5A mRNA, increased SCN5A splice variant abundances, decreased full-length SCN5A mRNA and protein, and decreased Na(+) current. These observations may shed light on a mechanism whereby cardiac function and arrhythmic risk are associated and allow for refined predictions of which patients may be at highest arrhythmic risk or suffer from Na(+) channel blocking anti-arrhythmic drug complications.

Celivarone in patients with an implantable cardioverter-defibrillator: adjunctive therapy for the reduction of ventricular arrhythmia-triggered implantable cardioverter-defibrillator interventions

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) remain the treatment of choice for the prevention of life-threatening arrhythmias. However, many patients with ICDs require additional antiarrhythmic therapy to reduce the morbidity associated with recurrent arrhythmia-triggered ICD interventions.

OBJECTIVE

Our study aimed to evaluate the safety and efficacy of celivarone in reducing these interventions.

METHODS

A total of 153 eligible ICD recipients were randomized to receive either placebo or celivarone 100 or 300 mg once daily for 6 months. The primary end point was the prevention of arrhythmia-triggered ICD therapies.

RESULTS

Fewer ventricular tachycardia and ventricular fibrillation episodes were observed in the 300-mg celivarone group than in the placebo group, with a relative risk reduction of 46%, which was not statistically significant. The analysis of all-cause shocks showed a trend toward a decreased number of events in the celivarone 300-mg group. A post hoc analysis of the primary end point in a subgroup of patients in the celivarone 300-mg group, who had received ICD therapy within 1 month of randomization, showed a significant benefit (P = .032). Celivarone was not associated with an increased risk of torsades de pointes, thyroid dysfunction, or pulmonary events. More heart failure events were reported in the celivarone groups than in the placebo group, but the difference was not statistically significant.

CONCLUSION

Celivarone tends to reduce ventricular tachycardia-/ventricular fibrillation-triggered ICD therapies. This effect was not statistically significant. There was a trend toward greater efficacy in the 300-mg group, especially in patients undergoing ICD therapy within 30 days prior to randomization. Overall, celivarone was well tolerated.

Use of implantable cardioverter-defibrillators

The implantable cardioverter-defibrillator (ICD) is the most effective treatment for patients with life-threatening ventricular tachycardia or ventricular fibrillation not due to reversible causes. The American College of Cardiology/American Heart Association class I and IIa indications for an ICD are discussed. Patients with ICDs who need pacing should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing, at a rate of 70/min. Patients with ICDs should be treated with β-blockers, statins and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

Chronic Suppression of Ventricular Tachyarrhythmias in Patients with ICDs

In this review, we examine the data evaluating the role of adjuvant therapy with antiarrthymic drugs (AADs) in chronic suppression of ventricular tachyarrhythmias in the patient with an ICD. It must be noted that all uses of AADs for this indication represent "off-label" prescription. No AAD is approved by the Food and Drug Administration (FDA) specifically as a therapy to reduce ICD shocks.